The present invention relates to electrical signal cables, and, more particularly, to a high performance electrical signal cable assembly and associated manufacturing methods.
Overtime home entertainment systems have grown increasingly better in terms of performance. Users have grown accustomed to high quality audio and video. Indeed, audiophiles and videophiles expect continuing improvements in the underlying technology to thereby yield improvements in the replication of audio and/or video entertainment.
An audio and/or video system may typically include a signal source, such as DVD player, etc. which generates signals based upon very accurate digital encoding. This digital coding may be converted into a low level analog signal, for example, to be delivered to a downstream power amplifier or switcher, for example. Certain signal sources may also transmit the signals in a digital form.
A cable assembly including a pair of connectors and a length of multiconductor cable is typically used to connect the audio and/or video signal source to the downstream power amplifier or signal switcher. The signals traveling along the cable may be effected by external noise sources, such as broadcast transmitters, wireless telephones, cellular telephones, etc. Internal material resistance may also effect the signals. Noise and distortion caused by the cable assembly become more significant as the quality and performance of the other related components continues to improve.
Relatively high performance cables including expensive conductor alloys and balanced configurations have been developed. The balanced configurations attempt to avoid the distortion which may occur in unbalanced systems, such as based on coaxial technology which include an overall shield surrounding one or more interior conductors. A coaxial cable may also have a relatively high capacitance and series inductance also leading to signal distortion.
An example of a high performance balanced cable is offered by Kimble Kable under the model designations AGDL and KCAG. The cables include three wire members arranged in a braided or interlaced construction. Each wire member may include a copper or silver conductor, and its own insulation layer. Various insulating materials including Teflon(trademark), polypropylene, polyethylene, polyvinyl chloride, silicone and others may be used. The braided arrangement is intended to keep the wire members together.
Unfortunately, one difficulty with the braided arrangement is that the braids may have a tendency to separate, especially adjacent the connectors. This makes handling more difficult and may adversely effect electrical performance. In addition, the cables require relatively complex braiding machinery which adds to the expense of the finished cable assembly.
In view of the foregoing background, it is therefore an object of the present invention to provide a high quality cable assembly that avoids wire member separation at the connectors, and which is more readily manufactured than conventional braided cables.
This and other objects, features and advantages in accordance with the present invention are provided by an electrical signal cable assembly including an electrical cable having opposing first and second ends connected to first and second electrical connectors respectively, and wherein the cable includes at least three wire members arranged in a non-interlaced configuration. More particularly, each wire member may comprise at least one metallic conductor and a respective individual insulating layer thereon. Each of the metallic conductors, in turn, may comprise at least one of silver and copper at a purity of greater than about 90 percent. Moreover, at overall insulating layer preferably surrounds the three wire members to retain them in position without requiring braiding. In addition, the overall insulating layer and the individual insulating layers are preferably transparent to show a metallic color of the metallic conductors therethrough.
In one embodiment, the non-interlaced configuration may comprise a helical configuration. Of course, the helical configuration may include portions with opposing rotational directions. In one class of embodiments, the at least three wire members comprises three wire members with centers defining vertices of an imaginary equilateral triangle at a given position along the cable.
The at least one metallic conductor of each wire member may comprise a single metallic conductor. Alternately, the at least one metallic conductor of each wire member may include a stranded metallic conductor.
The at least one metallic conductor of at least one wire member may comprise silver, such as silver at a purity of at least about 99.7 percent. Similarly, the at least one metallic conductor of at least one wire member may comprise copper. The copper may also be a relatively high purity of at least about 99.7 percent. Of course, both types of metal can be used in other cable embodiments.
The overall insulating layer may be directly on the three wire members so that the cable is devoid of a conductive shield. Accordingly, the cable retains its electrically balanced nature, and manufacturing is simplified.
Each of the individual insulating layers may comprise polytetrafluoroethylene, or Teflon(copyright), for example. The overall insulating layer may comprise polyvinyl chloride. Other plastics may also be used. The overall insulating layer may have a generally round outer shape which facilitates manufacturing and which may also make installation easier.
A method aspect of the invention is for making an electrical signal cable assembly. The method may include forming at least three wire members each comprising at least one metallic conductor and a respective individual transparent insulating layer thereon. Each of the metallic conductors may comprise at least one of silver and copper at a purity of greater than about 90 percent. The method may also include arranging the three wire members in a non-interlaced configuration, and forming an overall transparent insulating layer surrounding the three wire members to define an electrical cable. Also the method may include connecting first and second electrical connectors to respective opposing first and second ends of the electrical cable.